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Patented May 25, 1954 METHOD FOR REMOVING POLYMERS OF FURFURAL FROM METALLIC SURFACES Dwight L. McKay, Bartlesville, kla., assignor to Phillips Petroleum Company, a corporation of Delaware No Drawing. Application August 21, 1950, Serial No. 180,709

7 Claims. (01. 13440) 1 2 This invention relates to the dissolution of TABLE polymers which result from furfural. In oneof Solubility of Furfumz Polymer in Various its aspects this invention relates to a methodfor vents dissolving furfural polymers formed during the use of furfural as a selective or other solvent. P

. olymer In a more specific aspect the inventlon provides S M t Temp" Solubility, a novel solvent for the dissolution of said fur- O n grams/1100 t fural polymer. In one of its embodiments this grams so Ven invention comprises a step for the removal of furfural polymers which are deposited in heat I 223 i1 exchanger? and sllmces used in umiifittnttnatntat 3. .3 ass-.1... nectlon with certain selectlve solvent processes Monoemenolemme and acctone n77 10.9. particularly wherein hydrocarbons are selective- $3332 gg 3:8: ly extracted. Pyridine 240 3.0.

The use of furfural as a selective solvent in the 15 separation of hydrocarbons results in a deposition n Allpolymer charged to flask was dissolved. of furfural polymer on the metal surfaces of the fggggfgf g weight equipment employed and especially on the heat transfer surfaces of the distillation equipment, The above tests were made by heating polymer wherein the furfural is separated from the reand solvent at a constant temperature in a small covered hydrocarbon. Heretofore this polymer flask for a period of approximately four hours. has been removed by burning in the case of re- In some cases the solvent was refluxed at its boilmovable parts, such as the tube bundle in the furing point with a total condenser attached to the fural distillation column and by sand blasting flask. At the end of each heating period, the those surfaces which are not removable. These hot solution was filtered and the undissolved polymethods are obviously expensive and time conmer Weighed. suming and therefore are not resorted to until It was noted that upon cooling nearly all the t efljeieney of t process has been reduced dissolved polymer precipitated which facilitates to the absolute minimum as a result of these solvent recoveryfouled surfaces. Replacement costs of equipment It is noted that ethanolamme w h was are abnormally high as a result of these drastic employed m the experiments Summanzed m the methods of cleaning the fouled metal surfaces. above table gave especlauy good results at I have found that monoethanolamme, vated temperatures. Therefore, according to this ethanolamine and triethanolamine will satisfacgii 1t pi iq 2. p1 g i' the g torily dissolve and remove furfural polymers, a 1 e pnor 0 l S app ma lon 0 6 p0 ymer o eciau tho 8 hi h re f0 med h f rf m1 be dissolved and removed. Or, the ethanolamine y s W c a r W en u u may be applied to the surface, from which the 1s sub ected to elevated temperatures for expolymer is to be removed, for an extended period tended penods of tune I have also found that of time, or after application the surface itself can most of the alcohol amine can be recovered by 40 I I be heated. Indeed, the ethanolamine can be apdistillation without depositing the furfural polyplied to the urfa e after the u fa e and pO1y 011 heat transfer surfaces of the mer thereon have been preheated. When this is covery unit. done there is less time required for dissolution The table below shows the results of some tests of the polymer. However, ethanolamines whether conducted according to the invention. heated or not can be employed.

As stated, it is preferred to apply the solvent of the invention in preheated condition and when so applied it will be at a temperature in the approximate range 95 to 340 F., preferably 200 to 270 F., still more preferably 225 to 265 F.

The upper temperature limit will depend upon the decomposition temperature of the ethanolamine which in turn will vary with pressure, amount of dissolved polymer and other factors.

The solvent of the invention is readily substantially recovered by cooling to precipitate the polymer or by distillation from the dissolved polymer contained therein.

Reasonable variation and modification are possible within the scope of the foregoing disclosure and the appended claims to the invention the essence of which is that it has been found that an alcohol amine, as described, preferably preheated, is a good solvent for furfural polymer and therefore can be employed to remove said polymer from surfaces, e. g. in recovery units which have become fouled therewith and that said solvent can be readily and substantially recovered from the said dissolved polymer.

I claim:

1. A method for removing polymers of furfural from metallic surfaces which comprises contacting said polymers with an alcohol amine selected from the group consisting of monoethanolamine, diethanolamine and triethanolamine at a temperature in the range of 200 to 340 F. for a period of time of at least 4 hours.

2. A method for dissolving polymers of furfural which comprises contacting said polymers with an ethanolamine at a temperature in the range 200 to 340 F. for a period of time suflicient to dissolve said polymer.

3. A method for dissolving polymers of furfural which comprises contacting said polymers with an ethanolamine at a temperature in the range 250 to 310 F. for a period of about 4 hours.

4. The method of claim 1 wherein the alcohol amine is monoethanolamine and the temperature is in the range 225 to 265 F.

5. The method of claim 1 wherein the alcohol amine is diethanolamine and the temperature is in the range 225 to 265 F.

6. The method of claim 1 wherein the alcohol amine is triethanolamine and the temperature is in the range 225 to 265 F.

'7. A method for removing polymers of furfural from metallic surfaces which comprises contacting the said polymers with an alcohol amine selected from the group consisting of monoethanolamine, diethanolamine, and triethanolamine at a temperature above 95 F. and below the decomposition temperature of the alcohol amine for a period of time suflicient to dissolve said polymer.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,460,600 Sarbach Feb. 1, 1949 

1. A METHOD FOR REMOVING POLYMERS OF FURTURAL FROM METALLIC SURFACES WHICH COMPRISES CONTACTING SAID POLYMERS WITH AN ALCOHOL AMINE SELECTED FROM THE GROUP CONSISTING OF MONOETHANOLAMINE, DIETHANOLAMINE AND TRIETHANOLAMINE AT A TEMPERATURE IN THE RANGE OF 200* TO 340* F. FOR A PERIOD OF TIME OF AT LEAST 4 HOURS. 